\begin{tikzpicture}
 \begin{class}[text width=8cm]{ClassName}{0,0}
   \attribute{name : attribute type}
   \attribute{name : attribute type = default value}

   \operation{name(parameter list) : type of value returned}
   % virtual operation
   \operation[0]{name(parameters list) : type of value returned}
 \end{class}
\end{tikzpicture}